Oxymorphone and its corresponding 3-OH morphinan derivatives are conventionally produced by O-demethylation of oxycodone. The yield for these reactions varies, typically from 30% to as high as 80%. These reactions are less desirable than alternatives because the oxycodone starting material is expensive.
Alternatively, oxymorphone can be produced by oxidation of oripavine, followed by reduction of the intermediate, as illustrated in Scheme 1:

The route outlined in Scheme 1 is analogous to the method of making oxycodone from thebaine, which is widely practiced in the industry. The use of oripavine is desirable because O-demethylation of oxycodone is avoided. Unfortunately, the use of oripavine is challenging because of its multiple reactive sites by virtue of activating functional groups. The reactions of Scheme 1 yield significant by-products that cannot be easily isolated or removed, resulting in significantly lower reaction yields and purity rendering this synthetic route impractical on a commercial scale.
There exists therefore a need for an improved method of synthesis of oxymorphone and other morphinan derivatives that provides a significant yield improvement, as well as the option of a one-pot synthesis wherein the product is formed in a single reaction vessel without isolating the intermediate.